eBay Bi-cooler FMIC

Bicooler vs Aftermarket Stock Location


This post is a continuation of the evaluation of a Mk7 GTI bicooler intercooler arrangement compared to a stock location intercooler. The previous post compared the bicooler configuration (FMIC with stock GTI IC) with the stock GTI intercooler, this post will compare the bicooler with aftermarket stock location intercoolers.

Bicooler FMIC installed on Mk7 GTI
eBay Bi-cooler FMIC

The bicooler being evaluated is a Majesty FMIC, version 2 which is slightly thicker than version1, used in combination with the Mk7 GTI stock intercooler.

Note: This is not an evaluation for the following conditions:

Drag Strip
Road Course
Big Turbo

Conditions play a significant part in the performance measured from an intercooler. The matrix below shows a possible range of relevant conditions. Operating pressure is likely to be between 20 to 34 psi, and the length of time that the intercooler is subjected to heavy load can vary from a few seconds to several minutes. The colored squares are intended to convey the relative load the intercooler is operating under. Blue signifying light load, red a very heavy load. The data recorded for this comparison is limited to the top left portion of the operating conditions matrix. This means that the results may not be the same if the car were operated under different conditions.

The aftermarket intercoolers that will be used for comparison are from Wagner and APR.

Wagner Tuning Competition Intercooler
Wagner Tuning Competition Intercooler
APR Intercooler

Test – Airflow:

Products are tested with a flow bench and airflow is measured at a depression of 28″ of H20.

Mk7 GTI Stock IC with eBay FMIC Flow Test
Mk7 GTI Stock IC with eBay FMIC Flow Test

Flow test results are displayed in the bar chart:

Bicooler vs Stock Location Aftermarket Airflow

The three products are comparable, with the bicooler producing the highest airflow reading. Individual readings are:

  • Wagner – 255 CFM
  • Bicooler – 262 CFM
  • APR – 221 CFM

Test – Temperature

Multiple full throttle pulls in third gear are made starting around 2,000 rpm and continuing past 6,000 rpm. Using an IS38+ turbocharger the boost peak is around 28 psi and tapers down to around 25-26 psi. These pulls are made with each intercooler and are shown in the next three charts:

Bicooler multiple pulls:

Bicooler Multiple Pulls

Wagner multiple pulls:

Wagner IC Pulls
Wagner IC Multiple Pulls

APR multiple pulls:

APR IC Multiple Pulls

The overall trend for each intercooler is similar.

Analyzing the temperature rise is done by taking an Intake Air Temperature reading at 6,000 rpm and comparing with ambient to calculate the temperature delta. This reading is recorded several times to allow for calculating an average. This data is shown in the table below.

A statistical evaluation is made using a “t-test” to determine if there is a significant difference between the mean temperature above ambient of the compared intercoolers; first the Bicooler and Wagner, then the Bicooler and APR. The hypothesis is that the mean temperature delta is not different between the bicooler and aftermarket ICs.

The data recorded during this test does not show a significant difference between the mean temperature delta of the Bicooler versus aftermarket ICs.


The Majesty FMIC paired with a stock GTI IC in a bicooler arrangement was compared with Wagner and APR stock location aftermarket intercoolers.

The bicooler airflow is nearly within the margin of measurement error with the Wagner IC, but the bicooler flowed slightly more than the Wagner. The bicooler airflow is approximately 19% more than the APR IC (262 CFM vs 221 CFM).

In this test there was no significant difference in the temperature metric used to compare the Bicooler with the Wagner and APR intercoolers. Temperature results are significantly affected by test conditions and the results could be different under different conditions.

Overall the Bicooler performs similar to the Wagner and APR intercoolers using the measures and conditions of this test.


Wagner Intercooler product webpage

APR Intercooler product webpage

Majesty Intercooler eBay listing

t-test description

4 thoughts on “Bicooler vs Aftermarket Stock Location”

  1. Hi,

    I was curious which boost hoses you were using for the bicooler, just wanted to make sure I wouldn’t blow a hose off while driving.


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